This invention relates generally to mirrors comprising a myriad of reflecting surfaces so aligned with respect to each other as to produce one virtual image, which may be plain or focused. More particularly, it concerns mirrors of the type wherein said surfaces are irregular in outline to minimize or prevent glint patterns. Furthermore it relates to lenses comprising a myriad of lense surfaces so aligned with respect to each other as to produce one focused image.
This invention may be used in the construction of rear view mirrors (for automobiles) which afford 160.degree. or greater angle of rear and flank views from a mirror bracket only somewhat wider than a conventional rear-view mirror. This mirror will afford an undistorted image through the rear window, and smaller virtual images from the left and right flanks and sides of the vehicle.
Most existing mirrors are continuous reflecting surfaces which may be two-dimensional planar surfaces or three-dimensional curved surfaces (convex, concave or other). Conventional three-dimensional shaped mirrors are bulkier than planar mirrors by virtue of the additional materail needed to provide the third-dimension of the mirror surface. Commercially produced three-dimensional mirrors often have relatively large aberrations with attendant distortion of the images reflected therefrom. Reducing such distortions would significantly increase the cost of such mirrors.
In the past, mirrors have been proposed wherein multiple reflecting surfaces, offset from one another, have regular form, as in U.S. Pat. No. 3,739,455 to Alvarez. Due to such repetition of regular outlines of the reflecting surfaces, linear glint patterns may be discerned by the viewer. As a result, that type mirror is not well suited to the special mirror shapes, and uses disclosed herein, as for example rear view mirrors for vehicles enabling panoramic viewing of one or both rear flanks of the vehicle as well as toward the rear thereof, and other devices.
As described in U.S. Pat. No. 4,368,951 to Blom, the reflecting surface of a mirror may be segmented, comprising a myriad of reflecting surfaces so aligned or located with respect to each other to produce, in the eyes of a viewer, a virtual image, which may be plain or focused. As with a conventional mirror, the metallized surface of the segmented mirror may best be located where it is protected, i.e. on the back side of the transparent part of a mirror assembly, away from the viewer. The manufacture of such segmented mirrors may be accomplished by molding a transparent material in a suitable die. The die typically has one flat side opposite the side containing the sectors comprising the segmented mirror.
The main problem with segmented mirrors is that the viewer is bothered by optical interference which originates from the narrow zones separating the individual mirror sectors. Light is transmitted without distortion forward through the flat front of the transparent mirror assembly, and most of the light is reflected without distortion off the metallized sectors at the back of the mirror; however, that portion of the light transmitted to the back of the mirror which impinges on the thin zones separating the mirror sectors is reflected and refracted with uncontrolled geometry. These uncontrolled light eminations back toward the viewer tend to "fuzz" the definition of the virtual image he sees. These aberrations may take the form of linear glint patterns where the sectors of the mirror are in a regular geometric configuration, as in U.S. Pat. No. 3,739,455 to Alvarez. Or the aberration may be more diffuse as in U.S. Pat. No. 4,368,951 to Blom, where the sectors are irregular in outline.